The history of the bloodiest day ever for the U.S. Bureau of Alcohol, Tobacco and Firearms began more than eight months ago when, said Ted Royster, the agency began investigating Vernon Howell and activities at Mount Carmel.

Based on reports from local law enforcement officials at Mount Carmel’s neighbors, ATF agents knew Howell and his followers were heavily armed, perhaps with machine guns and homemade bombs, said Royster, special-agent-in-charge of the ATF’s Dallas field office.

Once the agency knew it had enough on Howell to make a move, agents from three of the ATF’s 21 field offices - Dallas, Houston and New Orleans – began rehearsing for Sunday’s air and ground assault. Part of ATF preparations was based on the agency’s knowledge of the layout of the compound, Royster said.

As late as Saturday, agents had practiced their assault on what they assumed was a heavily armed compound. Their search warrant spelled out that agents would be looking for various weapons and “homemade” explosives.

It appeared, Royster said, that Howell and his followers also were ready.

“We practiced for it, we drilled over and over again and we had our plan down,” he said.

“All of it went into effect, and they were waiting.”

Before they could barrel out of two large livestock trailers and two helicopters, more than 100 ATF agents and other officers were met by a barrage of gunfire from inside the Branch Davidians’ dormitory-style compound.

“It appeared that they knew we were coming,” Royster said.

Four ATF agents were killed and 14 wounded during the air and ground attack.

“The ATF has been around for a long time,” Royster said. “This is the largest loss we have sustained in one operation.”

ATF was created in 1972 to take over enforcement of laws related to alcohol, tobacco, guns and explosives that formerly had been the responsibility of the Internal Revenue Service.

About 120 agents of the ATF and its predecessor have been killed in the line of duty since Prohibition was imposed in 1919.

The ATF’s director reports to the assistant secretary of the Treasury for enforcement, along with the heads of other Treasury law enforcement agencies, including the Secret Service and the Customs Service.

Treasury Secretary Lloyd Bentsen, returning from a European trip Sunday, issued a statement saying the agents’ deaths “bring a profound sense of sorrow and loss.”

“But I have a strong sense of pride, too, for the selfless and heroic way in which they and their fellow agents carried out their duty in the face of great danger,” he added.

ATF agents from the Dallas, Houston and New Orleans offices were involved in the operation.

Royster said other local and federal agencies involved in the raid included the McLennan County Sheriff’s Department, the Federal Bureau of Investigation, the Immigration and Naturalization Service, Drug Enforcement Administration, the U.S. Customs Service and the U.S. Marshal’s Service.

The raid was coordinated from a command post at Texas State Technical College.

The gun battle erupted about 9:45 a.m. when the agents were met by a barrage of what sounded like automatic gunfire, possibly including that from large caliber weapons.

“There was heavy, sustained gunfire as they approached the compound,” Royster said.

Flying overhead were three helicopters from the Texas National Guard, two of which were hit.

Royster also said the National Guard provided other logistical support.

Tribune-Herald staff writer Tommy Witherspoon and the Associated Press contributed to this story.

Read the Tribune-Herald's 7-part investigative series on the inner workings of the Branch Davidians. Hours after Part 2 appeared in print, the ATF raided the group's compound.

Read the Tribune-Herald’s account of the ATF raid on the Branch Davidian compound on Feb. 28, 1993. Four ATF agents and six in the compound were killed in the gunfight.

Read the daily news accounts of the 51-day siege at the Branch Davidian compound near Elk, which began Feb. 28 and lasted until April.

April 19 and beyond: FBI agents began inserting canisters of tear gas into the Branch Davidian compound in the early morning hours. By noon, it was on fire.

Federal officials left the compound site in late May 1993. As identifications of bodies continued, questions about the survivors, the compound and the cult itself began to emerge.

As the world began to take a critical look back at the events and legal proceedings continue, the ATF's bombshell report forces a shakeup at the top after the raid gone "tragically wrong."

In 1994, the surviving Davidians went on trial in San Antonio. Over six weeks, more than 140 witnesses testified, with the verdict coming just two days prior to the anniversary of the ATF raid.

The Rodenville shootout and the 1988 trial, the end of the world in 1959 and more stories from deep in the Trib archives.